For the purpose of meeting requirements of increase in data services in future, an OTN is proposed, and the OTN integrates a capability of Operation, Administration, Maintenance and Provision (OAM&P), a transporting capability of a large-capacity and long-distance and a scheduling capability of a large-capacity.
Client services of the OTN include Constant Bit Rate (CBR) 2.5 G, CBR 10 G, CBR 40 G and General Framing Procedure (GFP). The OTN is able to provide transparent transportation for services with the above-mentioned CBR rates, and the transparence is mainly BIT transparence. When including LAN signals of Gigabyte Ethernet (GE) or 10 GE, the client signals are adapted to the OTN in a GFP protocol. The OTN is able to guarantee transparence on byte and frame of GFP signals as well as transparence on Media Access Control (MAC) frames of an Ethernet. The transparence on the MAC frames is a main requirement for transporting Ethernet data.
With the increase of data services and decrease of networking in such networks as Synchronous Digital Hierarchy (SDH) networks and Synchronous Optical Networks (SONETs), the Ethernet will be a primary data service in future. Two interfaces are defined in the Standard 802.ae of the Institution of Electrical and Electronics Engineers (IEEE). One is a 10 GE Wide Area Network (WAN) interface (10 Gbase-W) with a rate of OC-192/STM-64; the other is a 10 GE LAN interface (10 Gbase-R) using a 64B/66B coding. The 10 GE LAN interface, rather than the 10 G WAN interface, is adopted frequently in the interconnection of backbone routers or the interconnection of data switches because the cost of the 10 G WAN interface is high. Therefore, transporting 10 GE LAN services in the OTN is an important issue. The main problem in transporting the 10 GE LAN services in the OTN is that, the rate of a payload area in an Optical Channel Payload Unit 2 (OPU2) in the OTN is lower than the information rate of the 10 GE LAN service. In general, the information rate of the 10 GE LAN service is 10.0000±100 ppm Gbit/s, while the rate of the payload area in the OPU2 is 9.9953±20 ppm Gbit/s. Obviously, it is impossible to directly map the 10 GE LAN into the OPU2.
For the purpose of transporting the 10 GE LAN services in the OTN, some conventional technical solutions are proposed.
For example, with reference to FIG. 1, a 10 GE LAN signal is adapted via the GFP to a virtual concatenation signal with five OPU1s, i.e. OPU1-5V, and the virtual concatenation signals are transported in the OTN after being decoded by the 64B/66B decoding.
The disadvantage of the conventional method is that five OPU1s are needed. If a line rate is the rate of an Optical Channel Transport Unit 1 (OTU1), five color wavelengths are needed for transporting the five OPU1s. If the line rate is the rate of an OTU2, one OTU2 is used to transport four OPU1s, and one Optical Channel Data Unit (ODU1) in another OTU2 is used to transport the other OPU1. When a client wants to perform a bandwidth adjustment by taking one GE as a unit, because the rate of the OPU1 is 2.5 G, Link Capacity Adjustment Scheme (LCAS) is only able to perform the bandwidth adjustment by taking 2.5 G as a unit. The 2.5 G granularity in the conventional method is too large for the bandwidth adjustment wanted by the client. To sum up, the conventional method has a low efficiency and wastes bandwidth resources.